The influence of several anticancer drugs on the synthesis and methylation of nuclear and cytoplasmic RNA will be assessed in mouse and human tumor cell lines in vitro. 5-Fluorouracil, 5-fluorouridine, 5-azacytidine, dihydro-5-azacytidine, sangivamycin, formycin A, 8-azaadenosine and thiazole-carboxamide riboside will be examined. The influence of drug-modified messenger RNA on in vitro translation in a rabbit reticulocyte lysate will be studied following exposure of a human colon carcinoma (HT-29) cell line to 5-fluorouracil, 5-fluorouridine, sangivamycin and other nucleoside analogs. The anthracycline analog 5-iminodaunorubicin and 3'-deamino-3'-morpholino-daunorubicin will be examined in HT-29 cells with regard to cell viability, nucleic acid synthesis, drug uptake and efflux and DNA repair.